mirror of
https://github.com/nspcc-dev/neo-go.git
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compiler: support using return
in some branches
When `return` is used in one codepath, but not the other, we do not clean altstack properly. This commit fixes it.
This commit is contained in:
parent
2a6be8ceef
commit
b2a3cee451
3 changed files with 37 additions and 12 deletions
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@ -133,16 +133,13 @@ func (f funcUsage) funcUsed(name string) bool {
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return ok
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}
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// hasReturnStmt looks if the given FuncDecl has a return statement.
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func hasReturnStmt(decl ast.Node) (b bool) {
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ast.Inspect(decl, func(node ast.Node) bool {
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if _, ok := node.(*ast.ReturnStmt); ok {
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b = true
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return false
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// lastStmtIsReturn checks if last statement of the declaration was return statement..
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func lastStmtIsReturn(decl *ast.FuncDecl) (b bool) {
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if l := len(decl.Body.List); l != 0 {
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_, ok := decl.Body.List[l-1].(*ast.ReturnStmt)
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return ok
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}
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return true
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})
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return
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return false
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}
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func analyzeFuncUsage(pkgs map[*types.Package]*loader.PackageInfo) funcUsage {
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@ -261,8 +261,10 @@ func (c *codegen) convertFuncDecl(file ast.Node, decl *ast.FuncDecl) {
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ast.Walk(c, decl.Body)
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// If this function returns the void (no return stmt) we will cleanup its junk on the stack.
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if !hasReturnStmt(decl) {
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// If we have reached the end of the function without encountering `return` statement,
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// we should clean alt.stack manually.
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// This can be the case with void and named-return functions.
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if !lastStmtIsReturn(decl) {
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c.saveSequencePoint(decl.Body)
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emit.Opcode(c.prog.BinWriter, opcode.FROMALTSTACK)
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emit.Opcode(c.prog.BinWriter, opcode.DROP)
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@ -1,6 +1,7 @@
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package compiler_test
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import (
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"fmt"
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"math/big"
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"testing"
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)
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@ -132,3 +133,28 @@ func TestFunctionWithVoidReturn(t *testing.T) {
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eval(t, src, big.NewInt(6))
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})
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}
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func TestFunctionWithVoidReturnBranch(t *testing.T) {
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src := `
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package testcase
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func Main() int {
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x := %t
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f(x)
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return 2
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}
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func f(x bool) {
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if x {
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return
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}
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}
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`
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t.Run("ReturnBranch", func(t *testing.T) {
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src := fmt.Sprintf(src, true)
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eval(t, src, big.NewInt(2))
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})
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t.Run("NoReturn", func(t *testing.T) {
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src := fmt.Sprintf(src, false)
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eval(t, src, big.NewInt(2))
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})
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}
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